Adjustable, metered, directional flow control arrangements

ABSTRACT

A directional control valve is provided having a pair of standard work positions and a pair of extreme work positions and having a pressure compensating piston arranged between an input and a parallel input line controlling the flow to said control valve, said compensating valve acting as a check valve when the control valve is in its extreme positions and a flow dividing and control valve between the pressure compensating valve and an overflow outlet for delivering excess fluid to a separate load circuit.

United States Patent [191 Hodgson [451 Jan. 1,1974

[ ADJUSTABLE, METERED, DIRECTIONAL FLOW CONTROL ARRANGEMENTS [75]Inventor: Robert F. Hodgson, Canfield, Ohio [73] Assignee: CommercialShearing lnc.,

Youngstown, Ohio [22] Filed: June 14, 1972 [21] App]. No.: 262,460

[52] US. Cl. 137/101, 137/115, 137/118, 137/117 [51] Int. Cl. G05d 15/00[58] Field of Search 137/101, 114, 115, 137/117, 118

[56] References Cited UNlTED STATES PATENTS 3,179,120 4/1965 Erickson eta1 137/101 3,363,516 l/1968 Hubbard 137/101 X 3,410,295 1l/l968 Malott137/117 X 3,602,104 8/1971 Stremple 137/117 X 3,411,416 11/1968 Herdetal. 137/117X 3,455,210 7/1969 Allen 137/117 X 3,465,519 9/1969 McAlvayet a1. 137/117 X 3,561,327 2/1971 Stremple 137/115 X 3,703,186 11/1972Brewer 137/118 X Primary ExaminerWilliam R. Cline Attorney-Buell et a1.

[57] ABSTRACT A directional control valve is provided having a pair ofstandard work positions and a pair of extreme work positions and havinga pressure compensating piston arranged between an input and a parallelinput line controlling the flow to said control valve, said compensatingvalve acting as a check valve when the control valve is in its extremepositions and a flow dividing and control valve between the pressurecompensating valve and an overflow outlet for delivering excess fluid toa separate load circuit.

6 Claims, 2 Drawing Figures PATENTEDJAN 4 3.782.404

Fig.

Steering Valve 50 Implement V I I Valve ADJUSTABLE, METERED, DIRECTIONALFLOW CONTROL ARRANGEMENTS This invention relates to adjustable, metered,directional flow control arrangements and particularly to a flow controlarrangement for delivering pressure fluid to a steering circuit and aworking circuit for vehicles of the loading and excavating type.

The problems inherent in controlling the flow of fluid from a singlepump to both a metered demand circuit such as a steering circuit and afully demand circuit such as a loading circuit as well known. This is,however, a type of application frequently encountered in vehicles of theloading and excavating types which have hydraulic steering and hydraulicimplement (bucket) systems.

Directional control valves for controlling hydraulic fluid flow to andfrom a fluid actuated operator are old and well known. Such valves arecommonly used to deliver fluid to a piston and cylinder or other form offluid motor and are quite satisfactory for such purposes where the valveis fully actuated to an open or a closed position. Valves of this typeare not, however, adapted to provide a controlled metered flow to orfrom a fluid motor to operate the actuator at reduced or varied speeds.In general, the conventional control valve will produce a comparativelylarge change in flow rate for a very small change in position.

This problem has been recognized by others in this art and attempts tosolve the problem have been proposed in the patent literature. In Herdet al. U.S. Pat. NO. 3,41 1,416 a flow control arrangement is providedwhich overcomes some of the difficulties inherent in conventionalcontrol valves. Unfortunately, the arrangement of US. Pat. No. 3,41l,4l6 is adversely affected when an additional load circuit is connectedto receive excess flow from its pressure compensating valve. Backpressure at this point, due to the additional load circuit, will preventit from regulating the inlet flow through the spool valve in the mannerintended. Allen U.S. Pat. No. 3,455,210 recognizes this problem in Herdet al. and attempts to solve it by by-passing excess fluid flow awayfrom the directional control valve to the additional load circuitwithout adversely affecting the regulation of the speed of the actuator.However, experience has shown that the system of Allen while animprovement over Herd is subject to instability and poor regulation offlow to the primary actuator.

The principal difference between the Herd patent and the Allen patentlies in the fact that Allen substitutes a priority valve for a flowregulating valve of Herd with both being connected to an adjustableorifice which is controlled by the directional control valve spoolmovement.

A serious problem in all of these valve structures is that in the eventof a malfunction in the system, there is an insufficient supply of fluidto satisfactorily operate the steering circuit. This can result inserious accidents.

The present invention provides an adjustable metered directional flowcontrol arrangement which solves both the problems of the Herd et al.and the Allen patents as well as providing a safety system which willdivert all fluid to the steering in the event of a failure ormalfunction. The arrangement of this invention provides preciselycontrolled fluid flow to the primary actuator regardless of the amountof excess flow going to a secondary load circuit. This arrangement isaccordingly ideally suited to sue in a combination steering and loadcircuit for vehicles of the loading and excavating type.

I provide a directional flow control arrangement for selectivelyoperating first fluid operated motors at a controlled speed andsupplying overflow to a separate second fluid motor load circuitcomprising a pair of spacedfirst and second directional control valvemeans each having first and second motor ports for connection to theopposite sides of one of said fluid operated motors and operable toprovide a restricted inlet flow passage therethrough for passing inputpressure fluid to one of said motor ports the first of said valves beingconnected to said first motor means and having a parallel high pressurepassage, the second to said second motor means and return flow passagefor passing return fluid from the other of said motor ports, a pair offlow control valves connected to the inlet of each said directionalcontrol valve one having an inlet connected to a source of pressurefluid for said fluid motor through the inlet of said first directionalvalves, a controlled flow outlet port connected to the inlet of saidother flow control valve, an excess flow outlet port connected to saidparallel passages, valve means between said inlet port and both saidoutlet ports to control the fluid flow from said inlet to each of saidoutlet ports, means for operating said valve means in response to thefluid pressure drop across said inlet flow passage through said firstdirectional control valve means to control the division of flow fromsaid inlet port to said outlet ports, said other flow control valvehaving an inlet connected to said source of fluid pressure through saidone flow control valve and an excess flow outlet port connected to saidsecond directional control valve, valve means between said inlet andsaid outlet ports to control the fluid flow from said inlet to saidoutlet ports and means for operating said valve means in response tofluid pressure drop across said inlet flow passage through said firstdirectional control valve means to control the division of flow from theinlet means to said outlet means. Preferably the first directionalcontrol valve is provided with an extreme position at each end of itsspool movement connecting the inlet of the directional control valve inone such position with the parallel path and a first motor port and inthe other of said positions connecting the inlet of the directionalcontrol valve with the parallel passage and the second motor port,bypassing the flow control valves.

In the foregoing general description, I have set out certain objects,purposes and advantages of this invention. Other objects, purposes andadvantages will be apparent from the following description and theaccompanying drawings in which:

FIG. 1 is a sectional view of a preferred embodiment of a valvearrangement according to my invention;

FIG. 2 is a schematic view of a steering and implement circuit accordingto my invention.

Referring to the drawings 1 have illustrated a preferred embodiment ofvalve structure according to my invention as embodied in a combinationsteering and implement circuit such as is used on earth moving machines.In the drawings l have illustrated a directional control valve housing10 having an axial bore 11 carrying a valve member 12. The housing isprovided with spaced exhaust chamber 13 and 14 adjacent each end andintersecting bore 11, a pair of work chambers 15 and 16, one adjacenteach exhaust chamber and each adapted to be connected to the oppositesides of a fluid motor. Between the two work chambers are spacedparallel passage chambers 17 and 18 connected by a passage 60, sometimeshereafter called the parallel path" and between the parallel passagechambers a pair of inlet chambers 19 and 20 in side-by-side relationshipwhich when connected will sometimes hereafter be called the "open centerpath." The valve member 12 is hollow at each end to provide a pair ofspaced apart internal chambers 21 and 22 extending axially of the valvemember and each connected by a separate axial passage 23 and 24 and aseparate radial passage 25 and 26 to spaced annular grooves 27 and 28around the valve member 12 adjacent its mid point. Each of chambers 21and 22 is provided with two sets of radial passages 2la and 21b and 22aand 22b extending radially to the periphery of the valve member. Theradial passages 21a and 21b are spaced apart axially in chamber 21 asare also passages 22a and 22b in chamber 22. Passages 21a and 220 areseparated from passages 21b and 22b respectively by check valves 21c and22:: movable in chambers 21 and 22 respectively and operated by springs21d and 22d. lnlet chamber 19 is connected to a pump 29 for providing asource of high pressure fluid. lnlet chamber 20 is connected to inlet 30of flow control valve 31 which is in turn connected to inlet 40 of flowcontrol valve 41. lnlet 30 communicates with bore 32 of valve 31 whichis provided with valve member 33 biased to close the bore 32 between thepassage 37. The inlet 30 communicates at all times with outlet 34through annular chamber 31a. The bias is provided by a spring 35 and bya fluid pressure line 36. lnlet 40 communicates with bore 42 of valve 41which is provided with valve member 43 biased to close outlet 44 andprevent communication of outlet 44 with inlet 40. The bias is providedby spring 45 and fluid pressure line 46. Fluid pressure lines 36 and 46connect to a common annular manifold 47 in bore 11 of the directionalcontrol valve 10. Outlet 44 is connected to implement directionalcontrol valve 50 through its inlet where it joins the input line 51 froma second pump 52 providing an independent source of high pressure fluid.

The operation of the structure of FIGS. 1 and 2 as applied to acombination steering and implement control arrangement is as followsassuming a pump pressure available in excess of 60 psi. When there is noflow of pressure fluid in the system and the directional control valvefor steering control is in the neutral position, everything will beessentially as shown in the FIG. 1. The upper of the two flow controlpistons will be to the right, and the lower will be to the left, both ofwhich are spring biased. When the pump is started up and the spool 12remains in neutral, the flow will be around the spool 12 and around thefirst 33 of the two flow control spools through annular chamber 31a tothe annular groove 43a or reduced diameter area of the second spool atwhich time it is blocked monentarily. The second spool 43 will thenshift towards the right at approximately 60 psi because of the flow offluid in line 43b and begin to bypass oil on to the rest of the circuitthrough outlet 44, which in this case is primarily the lifting circuitfor the implement as represented by valve 50. The spring .end of thatflow regulating spool is vented to the reservoir through the line 46 ofthe spool as previously discussed. Any requirement of the implementcircuit then can be accommodated by the flow through this valve on tothe implement circuit, either by its singular supply from this pump orin conjunction with any other pump 52 which may be in this totalcircuit. The 60 psi drop will quickly disappear if the pressure risesabove that since the spring end is vented to the reservoir 60 and therewill be very little pressure drop then through this first valve in thecircuit which we will call the steering valve. At any time the implement circuit 50 is used by itself, there will be no appreciable ormeasurable loss of fluid in the steering circuit since that spool is inneutral and in all true sense of the word it could be considered aclosed center valve at this time.

The upper of the two flow regulating spools 33 is spring biased towardsthe right and also is vented to the reservoir by line 36 when thedirectional control valve spool 12 in this steering valve is in neutral;therefore, it will act as a check in certain cases. If we assume thatthe upper of the two flow regulating spools 33 has a 40 pound spring 35,it would be normal then for this spool 33 to shift to the left and closeoff any passage from the main open-center path 19, 20 to the parallelpath 17, 18, 60 from which power can be directed to either work port 15or 16 because of the fact that the spring end is vented to the reservoirwhich is at less than 40 or 60 psi. When the directional control spool12 is indexed towards the right, the passages within the spool will bealigned so that the parallel chamber 15 immediately adjacent to thisupper flow regulating valve 31 will be connected through to port 15except for the spring loaded check valve 210 within the spool. At thattime, the passage 23 within the spool 12 is also connected to the backof both of the flow regulating valves 31 and 41, both the upper and thelower, so that they then become pressure compensated. In effect, theyare pressure compensated in an opposite manner from each other. Thelower valve 41 is pressure compensated to regulate the exhausting orexcess oil. The upper outlet 37, to the left, will actually be shut offand will not start to open up until communication between the parallelpath 17, 60, 18 the center of the spool 12, the connecting or vent pathand the back of the spool 33 is completed at which time the circuit iscomplete and both ends of the spool are connected together via thepreviously mentioned route. At this moment the spring 35 will then pushthe spool to the right opening a path around the spool from the mainopen-center supply route from the pump to the parallel supply path 60 inthe valve itself. As soon as flow starts, there will be a pressure dropfrom this main supply path to the parallel path, and there will be asecond pressure drop from the parallel path 60 into the spool, both ofwhich will affect the total amount of flow being permitted to pass inthat direction and ultimately to port 15. For any intermediate positionof the directional spool, a pressure drop from the parallel passage 60into the center of the spool will be established. This will be matchedby the pressure drop established across the spool and the edge of thehousing metering the oil from the opencenter passage to the parallelpath 60 in opposition to the spring 35. However, since there is assumedan established 60 psi pressure differential available, the spool willshift beyond that point and attempt to put more oil to the parallelpassage. Now, the 40 psi drop will definitely be between the spool 33 ODand the spool 33 ID at the parallel passage 60 opening. The spool 33will continue to shift to the left until a 20 psi drop is establishedfrom the open-center passage to the reduced diameter area of the spool33, thereby establishing a total of 60 psi pressure drop from theopencenter passage to the center of the directional spool 12. This willbe balanced by the spring 35 and the differential pressure across therespective ends of the flow regulating spool 33. Any tendency of theexternal pressure to vary the amount of oil directed towards port willbe automatically adjusted to compensate for this by the shifting of theflow regulating spool 33. In short, the spool 33 meters flow in to theparallel path 60. It can be seen that the only oil taken from the(open-center) inlet chambers 19 and path in the steering device will bethat oil which is required and regulated by the steering directionalcontrol valve spool 12 and its associated compensator valve 31.

The shifting of the directional control valve spool 12 to the other side(left) will provide power to port 16 in like manner as that previouslydescribed for port 15. The oil returns from an exhaust port 13.

In the event that the steering system requires a higher pressure thanthe implement circuit, the operation will be the same whether this behigher than the operating pressure of the implement circuit or higherthan the open-center pressure when there is no demand on the implementcircuit. At this time, the second or lower pressure compensated spool 41is also connected to the respective side of the spool that is expectingpower for the port, and it will load at whatever pressure is required byhe steering circuit.

An additional feature which is available in the structure of thisinvention is the fact that the spool 12 can be shifted over and beyondthat normally required for metered control. When this is done in eitherdirection from neutral position, the full diameter of the spool which upto this point has been separating the opencenter path from the parallelpath is now shifted off to the right so that it blocks the open-centerpath 19, 20 completely at that point and opens the direct passage fromthe inlet 19 to the parallel path 17, 60. At this time all of the oilfrom the pump will be directed to the parallel path 17, 60 andsubsequently to port 15 via the spool 12 and check valve 21c. The lower41 of the two flow regulating valves is no longer a factor in thecircuit. The upper 31 of the two valves will now assume a position as acheck valve and block the escape of any oil from the parallel path 17,60 to the open center 20 and thereby preventing the oil fromsubsequently be coming a loss to the circuit. When the spool 12 is movedto the extreme left position, there is a passage opened up between theopen center 19 or pump inlet and the parallel path 17, 60 at the sametime that the full diameter of the spool at land 12a blocks theopencenter path 20.

it can readily be seen from FIG. 1 that the metered or regulated flowwill be available to the steering valve during under all normalconditions at whatever pressure is necessary. In the event of amalfunction of either the lower or upper flow regulating device,operation of the spool 12 to either extreme position will divert 100percent of the oil into the steering circuit directly, thereby providinga safety feature that would not be available in a purely pressurecompensated operation.

The implement valve 50 may be of the more common open-center type or itmay be pressure compensated since this method of control does not affectperformance of the steering valve. The steering valve 10 will takewhatever oil is necessary at its pressure regardless of what is going onat the balance of the circuit. In addition, the steering circuit takesonly that oil which it needs unless an emergency occurs at which timeall of the oil from pump is made available.

In the foregoing specification I have set out a present preferredembodiment of my invention, however, it will be understood that thisinvention may be otherwise embodied within the scope of the followingclaims.

I claim:

1. A directional flow control arrangement for selectively operating afirst fluid motor in two directions at a controlled speed and supplyingoverflow to a separate second fluid motor load circuit comprising adirectional control valve means (10, 11, 12) having an inlet means (19)and an outlet means (44) a parallel high pressure passage and first (15)and second (16) motor ports for connection to the opposite sides of saidfirst fluid operated motor, said directional control valve including amovable valve member (12) having annular grooves and axial borescooperating to provide a restricted inlet flow passage therethrough forpassing input pressure fluid to one of said motor ports (15, 16) andreturn flow passage (21, 21a-c; 22, 22a-e) for passing return fluid fromthe other of said motor ports, to an adjacent exhaust chamber (13, 14) apair of flow controls valves (31, 41) connected to the inlet (19) ofsaid directional control valve (10) one having an inlet (30) connectedto a source of pressure fluid for said first fluid motor through theinlet (19) for said directional control valve, an outlet port (34)continously connected to both the inlet (30) of the said one (31) and tothe inlet (40) of the other flow control valve (41 a parallel flowoutlet port (37) connected to said parallel passage (60), valve member(33) in said one valve (31) between said inlet port (30) and saidparallel outlet port (37) to control the fluid flow from said inlet (30)to said parallel flow outlet port (37), pressure responsive means (35,36) for operating said valve member 33 in response to the fluid pressuredrop across said inlet flow passage through said directional controlvalve, pressure sensing means (23-28, 36, 46, 47) acting on said valvemember to control the division of flow from said inlet port (30) to saidoutlet ports (37, 44), said other flow regulating valve (41) having aninlet (40) connected to said source of inlet pressure (19) around saidone flow control valve (31) and an excess flow outlet port (44)connected to said separate load circuit (50), a valve member (43) insaid other valve (41) between said inlet (19) and said excess flowoutlet ports (44) and pressure responsive means (45, 46) for operatingsaid valve means in response to fluid pressure drop across said inletpassage (19) through said directional control valve means.

2. A control valve as claimed in claim 1 wherein the valve member of thedirectional control valve is movable in a bore therein, said valvemember being hollow at each end to form chambers therein adaptedselectively to communicate through the valve member walls with the inletport, work ports, an outlet port and the pressure sensing port of thepressure compensating valve.

3. A control valve as claimed in claim 2 wherein said directionalcontrol valve member communicates with the pressure sensing port througha passageway between the two chambers in the neutral position andthrough a passageway in each chamber in each work position.

port to said second fluid motor load circuit when the pressure in thechamber exceeds the biasing means and pressure sensing pressures.

6. A control valve as claimed in claim 1 wherein the directional flowcontrol valve means has an extreme position at each end which directlyconnects the inlet and parallel passage with one of the motor ports.

1. A directional flow control arrangement for selectively operating afirst fluid motor in two directions at a controlled speed and supplyingoverflow to a separate second fluid motor load circuit comprising adirectional control valve means (10, 11, 12) having an inlet means (19)and an outlet means (44) a parallel high pressure passage (60) and first(15) and second (16) motor ports for connection to the opposite sides ofsaid first fluid operated motor, said directional control valveincluding a movable valve member (12) having annular grooves and axialbores cooperating to provide a restricted inlet flow passagetherethrough for passing input pressure fluid to one of said motor ports(15, 16) and return flow passage (21, 21a-c; 22, 22a-e) for passingreturn fluid from the other of said motor ports, to an adjacent exhaustchamber (13, 14) a pair of flow control valves (31, 41) connected to theinlet (19) of said directional control valve (10) one having an inlet(30) connected to a source of pressure fluid for said first fluid motorthrough the inlet (19) for said directional control valve, an outletport (34) continously connected to both the inlet (30) of the said one(31) and to the inlet (40) of the other flow control valve (41), aparallel flow outlet port (37) connected to said parallel passage (60),valve member (33) in said one valve (31) between said inlet port (30)and said parallel outlet port (37) to control the fluid flow from saidinlet (30) to said parallel flow outlet port (37), pressure responsivemeans (35, 36) for operating said valve member 33 in response to thefluid pressure drop across said inlet flow passage through saiddirectional control valve, pressure sensing means (23-28, 36, 46, 47)acting on said valve member to control the division of flow from saidinlet port (30) to said outlet ports (37, 44), said other flowregulating valve (41) having an inlet (40) connected to said source ofinlet pressure (19) around said one flow control valve (31) and anexcess flow outlet port (44) connected to said separate load circuit(50), a valve member (43) in said other valve (41) between said inlet(19) and said excess flow outlet ports (44) and pressure responsivemeans (45, 46) for operating said valve means in response to fluidpressure drop across said inlet passage (19) through said directionalcontrol valve means.
 2. A control valve as claimed in claim 1 whereinthe valve member of the directional control valve is movable in a boretherein, said valve member being hollow at each end to form chamberstherein adapted selectively to communicate through the valve memberwalls with the inlet port, work ports, an outlet port and the pressuresensing port of the pressure compensating valve.
 3. A control valve asclaimed in claim 2 wherein said directional control valve membercommunicates with the pressure sensing port through a passageway betweenthe two chambers in the neutral position and through a passageway ineach chamber in each work position.
 4. A control valve as claimed inclaim 3 wherein the passageways in each chamber communicates with theoutlet port when the valve is in neutral position.
 5. A control valve asclaimed in claim 1 wherein said other flow control valve member isbiased at one end to normally close the excess outlet port whilecontinuously communicating with the inlet port of both the directionalcontrol valve and the said one flow control valve, and dischargingthrough the excess flow outlet port to said second fluid motor loadcircuit when the pressure in the chamber exceeds the biasing means andpressure sensing pressures.
 6. A control valve as claimed in claim 1wherein the directional flow control valve means has an extreme positionat each end which directly connects the inlet and parallel passage withone of the motor ports.